AbstractMolecular mechanics calculations, using the AMBER program (version 3.0), are presented on the radiogenic electron‐capture radical formation in the crystalline chiral organophosphorus compounds (2R,4S,5R) and (2S,4S,5R) 2‐chloro‐3,4‐dimethyl‐5‐phenylphospholidine 2‐sulfide (respectively1and2). Geometry optimization of the corresponding radical anion structures and their respective crystal surroundings reveals an increase of the Van der Waals interactions, which is significantly larger in compound2than in1. This is in good agreement with previous single‐crystal ESR experiments and molecular interactions calculations without geometry o